2006 DODGE RAM 3500 Auto 4WD 5.9 DIESEL - NEED HELP diagnosing CAN bus

what is the best low cost scanner to trouble shoot a can bus issue ? I have a COMMS problem with my OBD2 port ? The speedo cluster passes the sweep test, but the CAN BUS related guage display ( tach, miles per hour, oil pressure, coolant temp) do not display on cluster. So, appears to be a wiring issue - would like to check for the presence of any CAN bus data - or look at the bus for noise-my OBDLINK MX+ will not read the port and cannot connect - 

Any thoughts about a break out cable ON the CAN bus source - the ECU - or better , just shoot out the wiring ? ANy ideas appreciated - thanks 

REM,

A scanner is not the right tool to diagnose can-bus problems. A solid understandiing of circuit design and working principles and a DVOM will take you a long way. At one point an osciloscope will be helpful to detect specific failure patterns.

after thinking about this - going to chase out the wiring -is there any scanners on the market to look at the waveform or the presence or not of a can bus signal ? thanks

Have you tried manually entering the VIN in the MX+ then installing Enhanced Diagnostics? IME the MX+ will stop if it can't find an ECM when you try to connect automatically. But it will communicate with other modules if you set the vehicle up manually.

If you can't get any direction with a scan the TIPM acts as the gateway for the three CAN networks so that'd be where I'd start testing.

thanks for the ideas - this vehicle not available in the pull down list - Ive asked for support from OBD2 link for manual install of VIN and also whether compliant with the dodge can bus enabled OBD2 port. . I put a new TIPM in this - reason, there are drying up fast on national backorder - there are now a handfull in the country left. But, as usual did not fix prob - digging into wiring today via all data .

If you select "Ram 1500" it brings up the 5.9 as an option   Maybe try that?

 

BTW I attached the factory network diagrams to my last post.

skipped over that - yes - Ill try that - thank you very much for the tip - one other thing - alphaobd is also a good app for chrysler - but havent tried it - tha

Put my DSO China Scope on it - looked at the CAN BUS wave forms - both CAN +/_ buses from ECM were dead - disconnected client modules on the bus and probed the two can bus pins in the bus between the ECM and TIPM connectors ( ie end to end) for continuity and each bus pin for continuity to ground. Turns out they were shorted to ground. Then I started opening connectors and tried to isolate the short. Turned out that the opening ABS module connector caused the short to alleviate. ( recall there was no comms at OBD2 diagnostic connector). SO going to probe the ABS splice off the main ECM to TIPM bus. Not sure if it is an internal short in the ABS module or it is the ABS branch. all normal functions returned except the ABS. Thanks for the response from those of you who offered some Ideas. Regards Rick

this was huge - thanks !!!!

BTW - have you used alphaobd ? - thanks

FIXED